Variations in the Activity of the Madden-Julian Oscillation:
Madden-Julian Oscillation: Recent Evolution, Current Status and … · 2017. 2. 13. ·...
Transcript of Madden-Julian Oscillation: Recent Evolution, Current Status and … · 2017. 2. 13. ·...
Madden-Julian Oscillation:
Recent Evolution, Current
Status and Predictions
Update prepared by: Climate Prediction Center / NCEP
13 February 2017
Outline
Overview
Recent Evolution and Current Conditions
MJO Index Information
MJO Index Forecasts
MJO Composites
The MJO is active, with both the RMM based and CPC velocity potential based
MJO indices depicting robust eastward propagation of an enhanced (suppressed)
convective envelope to the Western Hemisphere (Eastern Hemisphere).
The MJO is currently destructively interfering with the low-frequency state.
Dynamical model RMM index forecasts indicate continued propagation early,
followed by a reduction in amplitude. Some solutions depict rapid reemergence
of an enhanced signal over the West Pacific, possibly due to the evolving base
state.
The MJO is anticipated to influence the evolution of the global tropical
convective pattern. Impacts to the extratropics are uncertain given the
interaction between the MJO and an evolving low-frequency state.
Overview
Additional potential impacts across the global tropics and a discussion for the U.S. are available at:
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/ghazards/index.php
850-hPa Vector Wind Anomalies (m s-1)
Note that shading denotes the
zonal wind anomaly
Blue shades: Easterly anomalies
Red shades: Westerly anomalies
Westerly anomalies shifted
eastward across the
Maritime Continent to the
far western Pacific.
Easterly anomalies decreased in coverage over
the central Pacific.
850-hPa Zonal Wind Anomalies (m s-1)
Westerly anomalies (orange/red shading)
represent anomalous west-to-east flow
Easterly anomalies (blue shading) represent
anomalous east-to-west flow
Since late August, persistent westerly
(easterly) anomalies were evident over the
eastern Indian Ocean and western Maritime
Continent (central and western Pacific) as
shown by the red (blue) box at right. These
anomalies are low frequency in nature,
associated with the negative phase of the
Indian Ocean Dipole (IOD), and later, La Niña.
During mid-January, Rossby Wave activity
was evident, with destructive interference
on the base state evident through 100E.
Over the past couple of weeks, eastward
propagating anomalies were observed,
consistent with ongoing MJO activity.
OLR Anomalies – Past 30 days
Drier-than-normal conditions, positive OLR
anomalies (yellow/red shading)
Wetter-than-normal conditions, negative
OLR anomalies (blue shading)
During mid-January, the low frequency state
with enhanced (suppressed) convection over
the Maritime Continent (Indian Ocean and
Central Pacific) dominated.
In late January, enhanced convection
associated with the subseasonal state shifted
over the Atlantic and Africa, while the low
frequency background state persisted.
The low frequency pattern continued in early
February, though eastward propagation
associated with MJO activity was observed.
Enhanced convection developed over the
South Pacific during this time.
Outgoing Longwave Radiation (OLR)
Anomalies (2.5ºS - 17.5º S)
Drier-than-normal conditions, positive OLR
anomalies (yellow/red shading)
Wetter-than-normal conditions, negative
OLR anomalies (blue shading)
A low frequency state favoring enhanced
convection over the eastern Indian Ocean
and the Maritime Continent has been evident
since July (green box), with suppressed
convection over the Indian Ocean and near
the antimeridian (black boxes).
A fast eastward propagating convective
envelope was evident during early
September. Another intraseasonal event
occurred during late November and early
December. Each briefly interfered with the
background state.
Since late January, another eastward
propagating event has interacted with the
low frequency background as it shifted from
the Indian Ocean to the Maritime Continent
and West Pacific.
200-hPa Velocity Potential
Anomalies (5ºS - 5ºN)
Positive anomalies (brown shading) indicate
unfavorable conditions for precipitation
Negative anomalies (green shading) indicate
favorable conditions for precipitation
In late August and early September, intraseasonal
activity was apparent, before reversion to the low
frequency pattern associated with the negative IOD
and La Niña through late October.
During November, eastward propagation was
observed consistent with MJO activity on the fast
end of the intraseasonal spectrum.
After a break in intraseasonal activity during early
December, a signal emerged over the Maritime
Continent and has continued propagating through
the present.
The aforementioned intraseasonal signal
constructively interfered with the low frequency
state over the Maritime Continent near the
beginning of February.
IR Temperatures (K) / 200-hPa Velocity
Potential Anomalies
Positive anomalies (brown contours) indicate unfavorable conditions for precipitation
Negative anomalies (green contours) indicate favorable conditions for precipitation
Upper-level velocity potential anomalies continue to reveal a robust wavenumber-1 pattern, with
enhanced (suppressed) convection generally over the Western (Eastern) Hemisphere. This pattern
is now destructively interfering with the low-frequency state.
200-hPa Vector Wind Anomalies (m s-1)
Anomalous convergence is
now evident over the
Maritime Continent, with
fairly low-amplitude
anomalies over much of the
Tropics.
Note that shading denotes the
zonal wind anomaly
Blue shades: Easterly anomalies
Red shades: Westerly anomalies
A
A
200-hPa Zonal Wind Anomalies (m s-1)
After a quiet August, eastward propagation of
westerly anomalies was broadly consistent
with organized MJO activity during September.
In November, anomalous westerlies persisted
near the Date Line, though intraseasonal
variability associated with the MJO is evident.
In late November, easterly anomalies re-
emerged across the Indian Ocean and Maritime
Continent, consistent with the passage of sub-
seasonal activity and the re-alignment of the
low frequency base state.
Near the end of 2016 a period of westerlies
disrupted the low frequency state between
80-130E and continued propagating eastward
through the Western Hemisphere. This
subseasonal activity has continued, with
alternating anomalous westerlies/easterlies
being observed over the Pacific.
Westerly anomalies (orange/red shading)
represent anomalous west-to-east flow
Easterly anomalies (blue shading) represent
anomalous east-to-west flow
Weekly Heat Content Evolution
in the Equatorial Pacific
An eastward expansion of below average
heat content over the western Pacific is
evident through June, with widespread
negative anomalies building across the
Pacific over the course of boreal spring and
summer.
More recently, upper-ocean heat content
anomalies have been low amplitude,
consistent with the forecast transition to
ENSO-neutral conditions.
Oceanic Kelvin waves have alternating warm and
cold phases. The warm phase is indicated by
dashed lines. Downwelling and warming occur in
the leading portion of a Kelvin wave, and
upwelling and cooling occur in the trailing
portion.
The MJO index illustrated on the next several slides is the CPC
version of the Wheeler and Hendon index (2004, hereafter
WH2004).
Wheeler M. and H. Hendon, 2004: An All-Season Real-Time Multivariate MJO Index:
Development of an Index for Monitoring and Prediction, Monthly Weather Review,
132, 1917-1932.
The methodology is very similar to that described in WH2004 but
does not include the linear removal of ENSO variability associated
with a sea surface temperature index. The methodology is consistent
with that outlined by the U.S. CLIVAR MJO Working Group.
Gottschalck et al. 2010: A Framework for Assessing Operational Madden-Julian
Oscillation Forecasts: A CLIVAR MJO Working Group Project, Bull. Amer. Met. Soc., 91,
1247-1258.
The index is based on a combined Empirical Orthogonal Function
(EOF) analysis using fields of near-equatorially-averaged 850-hPa and
200-hPa zonal wind and outgoing longwave radiation (OLR).
MJO Index -- Information
MJO Index – Recent Evolution
The axes (RMM1 and RMM2) represent daily values of the
principal components from the two leading modes
The triangular areas indicate the location of the enhanced
phase of the MJO
Counter-clockwise motion is indicative of eastward
propagation. Large dot most recent observation.
Distance from the origin is proportional to MJO strength
Line colors distinguish different months
During the past week, continued eastward
propagation of an MJO signal was evident
across the Western Pacific into the Western
Hemisphere.
MJO Index – Historical Daily Time Series
Time series of daily MJO index amplitude for the last few
years.
Plot puts current MJO activity in recent historical
context.
GFS Ensemble (GEFS)
MJO Forecast RMM1 and RMM2 values for the most recent 40 days and
forecasts from the GFS ensemble system (GEFS) for the next
15 days
light gray shading: 90% of forecasts
dark gray shading: 50% of forecasts
The GEFS depicts eastward propagation
early, followed by reduction in amplitude
and subsequent reemergence over the
West Pacific.
The displacement of a counterclockwise
propagating signal in RMM phase space
could be a result of a changing base state.
Yellow Lines – 20 Individual Members
Green Line – Ensemble Mean
Spatial map of OLR anomalies for the next 15 days Time-longitude section of (7.5°S-7.5°N) OLR
anomalies - last 180 days and for the next 15 days
The GEFS prediction for RMM Index-based OLR
anomalies over the next two weeks shows a more
stationary pattern, possibly due to the forecast
evolution of the base state.
Figures below show MJO associated OLR anomalies
only (reconstructed from RMM1 and RMM2) and do
not include contributions from other modes (i.e., ENSO,
monsoons, etc.)
Ensemble GFS (GEFS)
MJO Forecast
The GEFS plot of MJO related
OLR anomalies is unavailable
at this time.
The GEFS plot of MJO related
OLR anomalies is unavailable
at this time.
Spatial map of OLR anomalies for the next 15 days Time-longitude section of (7.5°S-7.5°N) OLR
anomalies - last 180 days and for the next 15 days
Figures below show MJO associated OLR anomalies
only (reconstructed from RMM1 and RMM2) and do
not include contributions from other modes (i.e., ENSO,
monsoons, etc.)
Constructed Analog (CA)
MJO Forecast
The statistical (Constructed Analog) RMM-based OLR
anomaly prediction shows more canonical eastward
propagation of the MJO signal.
MJO Composites – Global Tropics
850-hPa Velocity Potential and
Wind Anomalies (Nov - Mar)
Precipitation Anomalies (Nov - Mar)
U.S. MJO Composites – Temperature
Left hand side plots show
temperature anomalies by MJO
phase for MJO events that have
occurred over the three month
period in the historical record.
Blue (orange) shades show
negative (positive) anomalies
respectively.
Right hand side plots show a
measure of significance for the
left hand side anomalies.
Purple shades indicate areas in
which the anomalies are
significant at the 95% or better
confidence level.
Zhou et al. (2011): A composite study of the MJO influence on the surface air temperature and precipitation
over the Continental United States, Climate Dynamics, 1-13, doi: 10.1007/s00382-011-1001-9
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjo.shtml
U.S. MJO Composites – Precipitation
Zhou et al. (2011): A composite study of the MJO influence on the surface air temperature and precipitation
over the Continental United States, Climate Dynamics, 1-13, doi: 10.1007/s00382-011-1001-9
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjo.shtml
Left hand side plots show
precipitation anomalies by MJO
phase for MJO events that have
occurred over the three month
period in the historical record.
Brown (green) shades show
negative (positive) anomalies
respectively.
Right hand side plots show a
measure of significance for the
left hand side anomalies.
Purple shades indicate areas in
which the anomalies are
significant at the 95% or better
confidence level.